Injected drug users are the largest group of people with hepatitis C infection. People who received a blood transfusion or kidney transplant before a diagnostic test became available form another large group of those infected.
Since human immunodeficiency virus (HIV) is also common among injected drug users and is transmitted sexually, about forty percent of HIV infected patients are co-infected with HCV. Various types of HIV such as HIV-1 and HIV-2 exist. Hepatitis C virus occurs in six known genotypes and more than fifty subtypes. The hepatitis C virus is harbored in the liver and most people infected with HCV eventually will develop cirrhosis or liver carcinoma. HCV can cause an acute or chronic infection. In chronic infection, the infected person can exhibit signs of chronic hepatitis or be a chronic asymptomatic carrier.
Current treatments for hepatitis C include interferons and other pharmaceuticals. However, because these treatments are not effective for all patients, improved methods for treating hepatitis C are being sought.